Subject:
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Re: Ball Clock (was: no subject)
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Newsgroups:
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lugnet.technic
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Date:
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Sat, 28 Feb 2004 00:51:35 GMT
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Viewed:
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4543 times
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In lugnet.technic, Bob Kojima wrote:
> i have just posted pics of my rolling ball clock on brickshelf:
>
> http://www.brickshelf.com/cgi-bin/gallery.cgi?f=73767
Saw this at Brickfest PDX. It is indeed quite impressive in person.
< snip >
> One
> problem that i have not solved yet is the lift mechanism is not 100%
> accurate. Very rarely, 2 balls are lifted at the same time or no balls are
> lifted at all. But i think that the no lifts and the 2 ball lifts even
> then selves out because after running for 3 days at Brickfest PDX it was
> only about 1 or 2 minutes off.
This is a problem you will probably not solve as long as there is a bin of balls
for the conveyor to draw from. The Seattle robotics guys will tell you that
getting soccer/basketballs to feed reliably from a bin is a non-trivial task.
Having built the original model in the 80s, I can tell you how it was solved in
the prototype. The balls must never enter a dump bin. By eliminating the dump
bin at the end of the return track, and lengthening the return track so that it
can accomodate the maximum number of balls (let's see, that would be 11+11+5=27
at 1:00), you should find that other balls do not interfere with the pickup
mechanism, and it should pick up one ball reliably each time.
You can test this theory by adding multiple pickup mechanisms (so you don't have
to wait 60 seconds per ball), then manually feed one ball at a time into the
bin. If your mechanism design can reliably pick up one ball every time, then you
know that eliminating the bin will work.
Hope that helps!
Great job. Ditto on every positive comment made in this thread.
Rick Clark
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Message is in Reply To:
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| i have just posted pics of my rolling ball clock on brickshelf: (URL) is an explanation: This clock is based on the Arrow Handicraft Deluxe Rolling Ball Clock that was popular in the 80's. To tell the time read the hour from the 3rd row of balls. (...) (20 years ago, 25-Feb-04, to lugnet.technic) !!
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